1. Field of the Invention
The present invention relates to an optical signal noise reduction device and a method of reducing optical signal noise. Especially the present invention relates to a device to reduce noise contained in optical binary pulse signals and a method of reducing noise of optical binary pulse signals. The optical signal noise can be reduced in optical processing using the present invention. Communication technique combined with the optical time division multiplex (OTDM) and wavelength division multiplex (WDM) are projected for increasing channel capacity. Optical code division multiplex (OCDM) attracts recently a good deal attention.
The OCDM is a communication system that a transmission site encodes signals with different time domain wave form for each channel, and a receiving site decodes the signals with the same key code. The system has a merit multiplexing many channels in the same time frame with the same wavelength. For developing the optical communication system such as the OCDM, it is needed to ameliorate signal to interference noise ratio for increasing the channel capacity.
2. Description of the Related Art
In prior art, the signal noise of the binary pulse signals is reduced in processing of electric signals transformed from the optical signals. That is, the noise reduction processing has not been carried in processing of optical signals, but the noise reduction process is carried for the electric signals transformed from the optical signals.
The prior art, however, causes a problem that the high-speed of the optical communication is decreased because of the transformation of optical signals to electric signals. Thus, even a new communication system such as the OCDM is adopted to increase the channel capacity, the system has not been employed effectively with the best use.